[waythenewsgoes]

He had a lot of acclaim as a young mathematician, according to Wikipedia he was taking college level math at 9 years of age. At this level of talent I believe you begin to be courted by top universities similar to D1 athlete's, not only that, but you are likely genius-level smart, so sticking you in a classroom of people your age would be doing you an intellectual disservice, similar to sticking a college freshman in a 2nd grade classroom. At this level, you are probably seen as the next Newton or Gauss, and professors will want to attach themselves to you and work alongside you. At this point you bring a ton of value to the school just for attending and they won't mind if you are testing out of course material since they are just happy for you to be there for any length of time, and it just becomes more of a formality anyway.